Drive and bearing for a shaft-less open-end spinning rotor

ABSTRACT

A device for an open-end spinning machine is disclosed having a drive and a bearing for a shaft-less spinning rotor that forms the rotor of an axial field motor. The device has a stator with a hollow, cylindrical core, a multiphase winding, and a combined magnetic/gas bearing. The bearing has gas outlet bores in an axial, plane-parallel bearing face providing for gas distribution symmetrically about the axis, and there are holding and centering magnets centered in the bearing face. The housings of the stator and the bearing are combined into a one-piece stator housing in which are formed the device for cooling, the gas distribution device, holders for spring and clamping elements of the stator housing suspension, and a support for a sensor plate. The housing also integrates a yoke plate of the bearing and connections for supply lines. A gas chamber therein is closed off on the open side by a gas bearing cover. The device housing has fitting elements and the spinning rotor is surrounded by a guide ring which forms an annular gap and limits its deflection out of the bearing center.

BACKGROUND OF THE INVENTION

The invention relates to a device for an open end spinning machine witha drive and bearing for a shaftless spinning rotor in accordance withthe preferred embodiment of the present invention. Such a device with adrive and bearing for a shaftless open end spinning rotor is known frompatent application WO 92/01096. Its combined magnetic-gas bearing withplane-parallel bearing faces is distinguished by extremely low frictionlosses and by a rotation around the axis through the center of gravitywhich is free of radial forces of the spinning rotor seated thereon inthe supercritical rpm range. Such a device is particularly suited fordriving very rapidly rotating spinning rotors. The construction of thedevice is still too expensive. It is also disadvantageous that, becauseof the many components, numerous joining tolerances can add up and inthis way the exact position of the spinning rotor axis in relation tothe axis of the take-off nozzle in the spinning machine can be impaired.The tolerance requirements, the costs of manufacturing and installationmake the known device expensive. It is not possible in this device toprevent damage to the spinning rotor in case of possible extremedeflections of the spinning rotor.

SUMMARY OF THE INVENTION

It is the object of the invention to remove these disadvantages, toimprove the operational dependability and the efficiency. It is alsointended to reduce the axial space requirements. The device is intendedto be suitable for driving spinning rotors of different sizes.

Briefy summarized, the stator core with its winding is fixedly seated ina one-piece stator housing made, for example, of injection-moldedplastic material. The housing for the gas bearing, the gas distributiondevice, areas for cooling the stator and the bearing as well as holdersfor the spring and damping elements of the stator suspension are alsoformed in this stator housing. This one-piece stator housing has theadvantage that seating tolerances which occur when several parts arejoined together are avoided. It is achieved in this way that themagnetic guide axis coincides with the axis through the center ofgravity, because inaccuracies on account of joining tolerances andmagnetic tolerances during assembly do not occur.

The yoke plate of the magnetic bearing and connections for the supplylines are integrated into the stator housing. On its open side, thechamber for the pressure gas in the stator housing is sealed by means ofa gas bearing cover. The combination of several parts and functions in acommon stator housing lowers the manufacturing costs of the device,because several work steps of positionally exact joining and gluing andof curing in-between are omitted. The improvements by means of the novelone-piece stator housing with the parts of the device formed thereonalso result in a more dependable device. The guide ring surrounding theinserted spinning rotor in an annular gap limits its possibledeflection, so that the spinning rotor cannot leave the field of theholding and centering magnets in the stator housing and instead isguided back into the bearing center.

In accordance with the preferred embodiment of the present invention, ayoke plate injection-molded into the stator housing has a threaded stemfor the gas bearing cover, and the gas bearing cover has a gas connectorwith a threaded bore.

In accordance with the preferred embodiment of the present invention thedimensional stability of the bearing is improved by means of reinforcingribs in the gas chamber of the stator housing.

In the embodiment in accordance with the preferred embodiment of thepresent invention, the housing of the device consists of an upperhousing part and a lower housing part, and the spring and dampingelements for the stator are formed in one piece with the lower housingpart.

In accordance with the preferred embodiment of the present invention,the holders of the stator housing are placed on bar springs seated inholders at the free end of plate springs of the lower housing part. Aone-piece embodiment of the stator housing and the lower housing part,in which the damped stator suspension is realized by means of elasticconnections of both housings, further simplifies the assembly of thedevice. This embodiment combines a compact structure with the elasticsuspension of the stator.

In accordance with the preferred embodiment of the present invention,the width of the annular gap between the guide ring and the insertedspinning rotor is of such a size that bucking of the spinning rotoragainst the spinning machine, for example when passing through thecritical rpm during free-wheeling slow-down, is assuredly prevented.

In accordance with the preferred embodiment of the present invention,the Hall sensors for motor control as well as the temperature sensorsfor controlling the bearing temperature are positioned and connected onthe sensor plate, which is embodied as a printed circuit foil. Bothtypes of sensors are located in the free winding gaps, whereinpreferably the temperature sensors are located in different winding gapsthan the Hall sensors. The connections of the sensor plate and of thewinding are each passed through segment-shaped openings in the statorhousing to a contact point.

A particularly effective heat dissipation out of the stator and the gasbearing is achieved by means of a cooling conduit in the area of thewinding, through which a coolant flows.

In a particularly simple embodiment, window-like openings in the statorhousing in the area of the winding are used for dissipating heat intothe ambient air. In both cases the good heat conducting ability of thewindings is used for cooling the bearing face.

In accordance with the preferred embodiment of the present invention, apressure distribution device in the bearing face, particularly forlarger rotor, is achieved in an advantageous and cost-effective mannerin that the outlet bores are located in the cross-sectional area of thecore of the stator, and that the gas distribution takes place, withoutinterfering with the eveness of the magnetic flux, in an annular gapwhich is formed by concentric partial cores and is closed off on bothsides by rings which are connected with each other, into which theoutlet bores can be easily cut.

An advantageous embodiment for special operational conditions isachieved in that the gas bearing is designed as a dual-circuit systemwith outlet bores in the area of the interior diameter and the crosssection of the stator core, wherein the two circuits can be operatedtogether or respectively individually with the same or different gaspressure. This embodiment makes possible different combinations by meansof which it is possible to meet the most varied demands in regard tooperational states or operational dependability. If one circuit isdisrupted, operational dependability is assured by the other.

In accordance with the preferred embodiment of the present invention,pressure sensors are provided which, in the single circuit gas systemand the dual circuit system, are disposed in the gas distribution deviceand in the annular gap or in the gas supply line. Specific monitoringand controllability of the bearing gas pressure is possible in this way.

By means of the method for positioning the bearing center of the deviceit is possible in a very simple manner to compensate uneveness in sizeand magnetism of the holding and centering magnets, which lead to adisplacement of the bearing center in accordance with which the axis ofrotation of the spinning rotor is aligned. In the installed state of thedevice this axis of rotation is determined with the aid of a fittedspinning rotor rotating supercritically, and is positioned and fixed ina centered position in relation to the fitting elements of the devicehousing. This is suitably done by means of an adjusting device, with theaid of which the axis of rotation of the spinning rotor can bedetermined and brought into the centered position in relation to thefitting elements for the spinning machine.

In accordance with the preferred embodiment of the present invention,positioning is performed by displacing the lower housing part inrelation to the upper housing part, which is inserted into the spinningmachine.

The present invention further comprises recite different embodiments ofthe fitting elements in relation to which the stator is centered inaccordance with the process.

The reduction of the many individual parts of the device also decreasesits structural space requirements.

Some exemplary embodiments of the invention are represented in thedrawings and are described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1, a longitudinal section through the device with a single circuitgas system;

FIG. 2, a top view on the stator without the device housing and with twopartial cutouts in the stator housing;

FIG. 3, a longitudinal section through the stator housing and the lowerhousing part in an embodiment having a one-piece common housing;

FIG. 4, a longitudinal section through the stator with a dual-circuitsystem;

FIG. 5, a longitudinal section through the two rings of the embodimentof FIG. 4;

FIG. 6, a top view on the upper ring of the embodiment of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows a longitudinal section through the device with fittedspinning rotor 1, which has been positioned in a spinning machine, notshown, in such a way that the axes of rotation and of the draw-offnozzle are aligned. A core 2 of the stator with a multi-phase winding 3has been securely and sealingly cast with a sealing compound 5 into aone-piece stator housing 4.

The following elements are combined into one part in or are formed on astator housing 4:

A gas bearing housing with a gas distribution device 6, a coolingconduit 7 for cooling the stator and a bearing face 8, a holder 9 forthe spring and damping elements 10, 11, a support 12 for a sensor plate13. A yoke plate 14 for the holding and centering magnets 15 andconnections 16 for supply lines 17 are integrated into the statorhousing 4. On the side of the stator facing the rotor, the sealingcompound 5, together with the wall of the stator housing 4 and theholding and centering magnets 15, forms the plane-parallel bearing face8. In it terminate outlet bores 19, coming from a gas chamber 18 andlocated closely at its edge.

The open side of the gas chamber 18 in the stator housing 4 is sealed bya gas bearing cover 20, having an injection-molded connector 21containing a threaded bore. The gas bearing cover 20 is screwed togetherwith a threaded stem 22 of the yoke plate 14 which was injection-moldedin the stator housing 4. The gas chamber 18 of the stator housing 4 isreinforced by ribs 23 located in the interior. The sensor plate 13,embodied as a flexible printed circuit foil, rests on the support 12 ofthe stator housing 4 and is fixed in place by the sealing compound 5.The winding connections 24 are passed out through segment-shapedopenings in the stator housing 4 and are connected, together with thesensor plate 13, at a contact point 25.

The elastic suspension of the stator consists of the spring and dampingelements 10 and 11, which are embodied as plate springs 10,injection-molded on a lower housing part 26 of a device housing 27, andon the free ends of which bar springs 11 have been formed. The barsprings 11 are locked into the holders 9 of the stator housing 4.

The centering collar of the device housing 27 is used as the fittingelement 28 for the installation of the device into the spinning machine.The bearing center, defined by the holding and centering magnets 15, ispositioned in relation to it in that it is determined with the aid ofthe spinning rotor supercritically rotating in the installation positionof the device, is brought into a centered position by radiallydisplacing the lower housing part 26 in relation to the upper housingpart 29 and is fixed there by connecting screws 30 of the device housing27.

The device operates as follows: an equilibrium is formed between the gaspressure and the magnetic force of the holding and centering magnets 15,so that the spinning rotor can rotate contactless around the axisthrough its center of gravity. So that the spinning rotor 1 can passwithout problems through critical rpm, the oscillations occurring in thecourse of this and transmitted via a rigid magnetic guidance to thestator are damped by its elastic suspension in the device housing 27.The spinning rotor 1 is enclosed by a guide ring 32 of the devicehousing 27 which forms an annular gap 31 and limits the rotordeflection, for example at the critical rpm.

FIG. 2 shows the stator in a top view with two partial cutouts in itsstator housing 4. The connections 16 of the supply for the coolingconduit 7 and integrated into the stator housing have been made visiblein one cutout. The other cutout shows the winding 3 located under thesealing compound 5 and the sensor plate 13 with a sensor 33 in thewinding gap 34. The combined magnetic-gear bearing 35 is shown in thecenter as rings; a circle of gas outlet bores 19 is visible in thestator housing around the ring-shaped holding and centering magnets 15.The sensor plate 13 is brought to the contact point 25 through asegment-shaped opening in the stator housing 4.

FIG. 3 shows an embodiment with a one-piece stator and device housing inlongitudinal section. The stator housing 4 and the lower housing part 26are one common part, wherein connections 36 as spring and dampingelements are placed between the two. Positioning of this one-piecehousing takes place with the same means of the described exemplaryembodiment.

FIG. 4 shows the exemplary embodiment of a stator with a gas bearing 35as a dual-circuit system, wherein the outlet bores 19 of the one circuitare located in the area of the interior diameter of the core 2 and theoutlet bores 37 of the second circuit are located in the cross-sectionalarea of the core 2. Depending on the operational requirements, the twocircuits can be connected individually or together and with the same ordifferent gas pressure. The core 2 consists of two concentric partialcores 38, 39, which form an annular gap 40 for gas distribution andwhich is sealingly closed at both ends by rings 41, 42. These are shownin greater detail in FIGS. 5 and 6.

FIG. 5 shows the two rings 41, 42 in longitudinal section. The upperring 41 is connected with the lower ring 42 by bars 43, the thickness ofwhich is less than the width of the annular gap 40. The upper ring 41has axial projections 45 for the outlet bores 37. Following assembly,the axial projections 45 are located in winding gaps 34 of the statorand are of the length of the cast winding 3. The lower ring 42 has a gasinlet opening 46 which can be connected with a connector 44.

FIG. 6 shows a top view of the upper ring 41, the bars 43 can be seen inthree cutouts. The axial projections 45 which, after installation of thestator, terminate in the bearing face 8 are shown with the outlet bores37 on the upper ring 41.

The exemplary embodiment in accordance with FIG. 4 can be simplified forspinning rotors with larger diameters by doing away with the inner gasbearing circuit. Because of this, the inner outlet bores 19 and the gasbearing cover 20 with the connector can be omitted. If the outlet bores37 are located in the cross-sectional area of the stator, a gas pressuredistribution is obtained which is adapted to the larger rotor diameter.

We claim:
 1. A device for an open end spinning machine with a drive andbearing for a shaftless spinning rotor forming the rotor of an axialfield motor, wherein the device comprisesthe stator with a groovelesshollow-cylindrical core and a multiphase winding and with sensors fordetecting the spinning rotor position in gaps of the winding and acombined magnetic-gas bearing with gas outlet bores in an axial,plane-parallel bearing face, axis-symmetrical gas distribution andholding and centering magnets disposed centered in the bearing face andmeans for cooling the stator and the magnetic-gas bearing as well as anelastic, damped stator suspension on a device housing, characterized inthat the housings of the stator and the gas bearing are combined into aone-piece stator housing (4), in which are formed the means for cooling(7), the gas distribution device (6), holders (9) for the spring anddamping elements (10, 11) of the suspension of the stator housing (4),and a support (12) for the sensor plate (13), and in which a yoke plate(14) of the magnetic bearing (35) and connections (16) for supply lines(17) are integrated and wherein a gas chamber (18) is sealing closed offon the open side by a gas bearing cover (20) and is reinforced in theinterior by ribs (23), and the device housing (27) has fitting elements(28) adapted to the spinning machine and the spinning rotor (1) issurrounded by a guide ring (32) which forms an annular gap (31) andlimits its deflection out of the bearing center.
 2. A device inaccordance with claim 1, characterized in that the yoke plate (14),having a threaded stem (22), is injection-molded on the stator housing(4), and a gas connector (21) with a threaded bore on the gas bearingcover (20), and the stator housing (4) and the gas bearing cover (20)are sealingly screwed together.
 3. A device in accordance with claim 1,characterized in that the device housing (27) consists of an upperhousing part (29) and a lower housing part (26) with connecting springand damping elements (10,11), wherein these elements (10, 11) are formedout together with the lower housing part (26).
 4. A device in accordancewith claim 3, characterized in that the spring and damping elements (10,11) are embodied as plate springs (10) on the lower housing part (26)and as bar springs (11) seated between the holders (9) on the statorhousing (4) and the plate springs (10).
 5. A device in accordance withclaim 3, characterized in that the stator housing (4) and the lowerhousing part (26) are made of one piece, wherein connections (36)between them are embodied as spring and damping elements.
 6. A device inaccordance with claim 1, characterized in that an annular gap (31)between the guide ring (32) and the inserted spinning rotor (1) isnarrower than its distance from the spinning machine.
 7. A device inaccordance with claim 1, characterized in that the sensor plate (13) isembodied as a flexible printed circuit foil, on which Hall sensors (33)for motor control and temperature sensors are positioned close to themagnetic-gas bearing (35) and are connected, and the stator housing (4)has segment-shaped openings through which winding contacts are passed toa contact point (25).
 8. A device in accordance with claim 1,characterized in that the area of the winding (3) a cooling conduit (7),through which a coolant flows, has been embodied for means for coolingthe stator and the gas bearing.
 9. A device in accordance with claim 1,characterized in that the area of the windings (3) the stator housing(4) has openings which are provided for a directed heat dissipation tothe ambient air.
 10. A device in accordance with claim 1, characterizedin that outlet bores (37) are located in the cross-sectional area of thecore (2) of the stator, and that it consists of two concentric partialcores (38, 39) which form an annular gap (4) for gas distribution, whichis closed off on both sides by rings (41, 42) which are connected witheach other by bars (43), the thickness of which is less than the annulargap width, that the upper ring (41) has axial projections (45) for theoutlet bores (37), which are located in the winding gaps and have theheight of the cast winding, and that in the area of the outlet bores(37) the upper ring (41) has cutouts for shortening the bore length, andthat the lower ring (42) has a gas inlet opening (46) which is connectedwith a connector (44).
 11. A device in accordance with claim 1 or 10,characterized in that the gas bearing (35) is embodied as a dual-circuitsystem, wherein outlet bores (19) of the one circuit are located in thearea of the interior diameter of the core (2) and outlet bores (37) ofthe second are located in the area of a cross section, and that the twocircuits can be connected individually or together, with the same ordifferent gas pressures, depending on the operational requirements. 12.A device in accordance with claim 10, characterized in that pressuresensors are provided in the single circuit or dual-circuit systems inthe gas supply lines or in the gas distribution device (6) and in theannular gap (40) for monitoring the gas pressure for the gas bearing(35).
 13. A device in accordance with claim 1, characterized in that thedevice housing (27) consists of an upper housing part (29) and a lowerhousing part (26), which for centering can be displaced in relation toeach other and fixed in place, wherein the lower housing part (26)contains the connecting elements to the stator and the upper housingelement (29) the fitting elements (28) to the spinning machine.
 14. Adevice in accordance with claim 13, characterized in that the fittingelements (28) of the device housing (27), which are adapted to thespinning machine, are selectively embodied as a centering collar on theupper housing part (29) or as pin bores or pegs.
 15. A device inaccordance with claim 13, characterized in that when the device housing(27) has been fitted free of play, cuttingly processed fitting surfaces,which are positioned in respect to the bearing center, are disposed onits upper housing part (29).
 16. A device for an open-end spinningmachine having a drive and a bearing for a shaftless spinning rotor (1)representing the rotor of an axial field motor, wherein the devicecomprises a stator having a hollow-cylindrical core (2) and a winding(3) and a combined magnetic/gas bearing with gas outlet openings (37) inan axial bearing face (8) arranged for axis-symmetrical gasdistribution, wherein the core (2) of the stator comprises twoconcentric partial cores (38,39) forming an annular gap (40) for the gasdistribution and the gas outlet openings (37) are located in thecross-sectional area of the core (2) of the stator at the gap (40). 17.A device in accordance with claim 16, wherein the annular gap (40) isclosed at opposite sides by rings (41,42) which are connected with oneanother by bars (43) having a thickness less than the annular width ofthe gap (40).
 18. A device in accordance with claim 17, wherein one ring(41) has axial projections (45) for the gas outlet openings (37), thegas outlet openings (37) being located in gaps in the winding (3).
 19. Adevice in accordance with claim 18, wherein the one ring (41) hasrecesses for shortening the bore length in the area of the gas outletopenings (37).
 20. A device in accordance with claim 17, wherein onering (42) has a gas inlet opening (46) communicated with a connectorelement (44).
 21. A device in accordance with claim 16, wherein the gasbearing (35) comprises a dual-circuit system having outlet bores (19)located in the area of the interior diameter of the core (2), the twocircuits being connectable individually or together, at the same ordifferent gas pressures, depending on the operational requirements forthe device.
 22. A device in accordance with claim 21, wherein pressuresensors are provided in the single circuit dual-circuit systems in gassupply lines or in a gas distribution device (6) and in the annular gap(40) for monitoring the gas pressure for the gas bearing (35).